How to calculate the CGT if selling a oversea property

As far as I understand the CGT is the differences amount between the buying price and selling price, is it as simple as to calculate the CGT by difference between prices in foreign currency and convert it to GBP. Also, will there be any time limit required by HMRC for report the selling or it is also acceptable to report it within the taxation period?

Hi,
Yes to point 1.
The sale needs to be reported within the taxation period as it is a foreign sale and does not fall under the 60 day reporting period.
Thank you.

Hi, How to refer the exchange rate from foreign currency to GBP, the exchange rate of the trading day or there is other exchange rate for references.

Hi WH,
HMRC rates are at  HMRC currency exchange average rates - GOV.UK (trade-tariff.service.gov.uk) 
Thank you.